Healthy Aging

Vitamin D vs. Vitamin D3 Supplements: Are They The Same?

Bone & Muscle Defense

Bone & Muscle Defense

Derived from the amino acid leucine, myHMB®️ is a highly concentrated, proprietary breakthrough in muscle support and protection. Along with myHMB®️, Bone and Muscle Defense also contains the patented nutrient OsteoSine®, to support healthy bones, and is rounded out with clinical dosages of Vitamin D3, a potent and patented form of K2 called K2Vital®, Magnesium, and L-Carnitine, for the most complete bone and muscle support formulation available today.


Vitamin D vs. Vitamin D3 Supplements: Are They The Same? about Bone & Muscle Defense

Vitamin D vs. Vitamin D3 Supplements: Understanding the Differences and How To Boost Health Benefits

You've probably heard of vitamin D called the "sunshine vitamin." It earned the nickname because your skin produces vitamin D when it's exposed to sunlight. In fact, around 90 percent of vitamin D in your body comes from the sun! It's vital for everything from boosting your brain cell activity and muscle function to promoting a healthy, happy mood. 

However, the recommendation by medical authorities to "keep out of the sun" or, if you do sunbathe, to slather yourself with sunscreen has led to what one expert calls a vitamin D "deficiency pandemic." As a result, supplementing with vitamin D to raise your intake has become vital if you hope to stay well and avoid a host of potential health problems.

But since two forms of the vitamin are available, which should you take, vitamin D2 or vitamin D3? What's more, how can you make sure you're getting enough to truly support your health?

Key Takeaways

  • Vitamin D may be an essential vitamin, but deficiency abounds-- even if you take a multi-vitamin. Since vitamin D is naturally found in limited quantities in only a small number of foods, it's important to take vitamin D as a dietary supplement to maintain your overall health.

  • Both forms - vitamin D2 and D3 - are available and will raise blood levels, but D3 is more efficient in this regard. In addition, vitamin D3 also works differently than D2 and can better support human health.

  • Vitamin D blood levels, according to experts, should be above 40 ng/mL, and ideally a good deal higher than that. Testing your blood is essential in order to find out where you stand and what strategy would work best to raise your vitamin D levels and maintain them.

Vitamin D: The Bone Health Vitamin That's So Much More

Vitamin D is a fat-soluble vitamin. You've heard that it's essential for bone health, but what you may not know is that it's also an essential micronutrient that supports your immune system, your heart and lung function, and your endocrine system—the part of your body that's involved in hormone regulation.

Vitamin D has two primary forms: vitamin D3 or cholecalciferol, and vitamin D2, often called ergocalciferol. When they enter or are produced by your body, your liver converts them to 25-hydroxyvitamin D or 25(OH)D. 25(OH)D is considered the best blood marker of your overall vitamin D status. It reflects both what your body makes through sun exposure, as well as the vitamin D you obtain through your diet and supplementation.

While D2 and D3 are both referred to as "vitamin D", they aren't the same.

What's The Difference Between Vitamin D and Vitamin D3?

For many years vitamin D2 and vitamin D3 were thought to be equal. After all, they both play the same vital role in the body- or so doctors thought. Even today, the medical field doesn’t distinguish between vitamin D2 and vitamin D3. Yet, when doctors talk of vitamin D they're usually talking about the form they usually prescribe, which is vitamin D2.

However, it’s now becoming increasingly clear that the slight differences in the molecular structures of the two forms of vitamin D are actually significant when you consider how they function in your body. 

In fact, the differences between the two mean that they:

  • Are metabolized differently

  • Have different effects on the immune system

  • Express genes differently

  • Bind to their target molecules in different ways or bind to the same target molecules but with differing efficiencies

  • Raise vitamin D status in the blood by differing amounts

The last point has been demonstrated in many studies from around the world.  And it's the reason that so many people seek out vitamin D3 instead of vitamin D2.

Vitamin D3 Raises Blood Levels More Effectively

A study reported in The American Journal of Clinical Nutrition found that "vitamin D3 is more efficacious at raising serum 25(OH)D concentrations than is vitamin D2, and thus vitamin D3 could potentially become the preferred choice for supplementation."

More proof of the power of D3 was found by a second meta-analysis comparing the effects of the two forms of the vitamin as the researchers concluded that, "Vitamin D3 leads to a greater increase of 25(OH)D than vitamin D2."

In a similar study, UK nutritional scientists wrote that “vitamin D3 was more effective than vitamin D2 in increasing serum 25(OH)D in the wintertime. Vitamin D3 may therefore be a preferential form to optimize vitamin D status within the general population.”

Overall, the results showed that those who were given vitamin D3 benefitted from an average increase in vitamin C status of up to 75 percent.  This is compared to an average increase of just 33 percent in vitamin D status for study participants who took vitamin D2.

These studies clearly illustrate that when it comes to vitamin D2 vs. D3, the latter is the superior form for raising blood levels.

Health Benefits of Vitamin D and Vitamin D3

Many people don't realize just how critical vitamin D is to achieving healthy, disease-free aging. While we could write an article on each of these remarkable health benefits of vitamin D, today we'll provide only a brief summary of some the most important research.

Cancer Prevention

Research way back in the 1940s found that geography, and a person's access to sunlight, played a role in their cancer risk. The further north you lived, the more likely you were to be diagnosed with some form of cancer. Author Richard Hobday wrote about this in his book, The Healing Sun. Since then, more research has shown that vitamin D prevents cancer in four important ways. Vitamin D:

  1. Regulates the growth and death of cells, including cancer cells.

  2. Controls cell differentiation so your cells remain “normal”.

  3. Regulates new blood vessel formation so it can choke off a tumor’s blood supply.

  4. Increases oxygen supply to cells and tissues so healthy, normal cells thrive.

A major review covering 50 trials of cancer incidence found vitamin D reduced the risk of cancer by 15 percent, but this only applied to the D3 form and not D2.

Healthy vitamin D levels also benefit patients with cancer. A UC San Diego study found breast cancer patients with high levels of vitamin D in their blood were twice as likely to survive the disease as women with low levels. Good vitamin D status is also linked to improved survival in colorectal and lymphoma patients.

Bone Health

Strong bones begin with calcium and vitamin D. In fact, your bones can't absorb calcium and use it for bone mineralization and growth without vitamin D. Studies show that people with vitamin D deficiency may absorb as little as ten to 15 percent of dietary calcium. That can double or triple in those with optimal vitamin D levels. What's more, if you're deficient in vitamin D and you can'b absorb calcium, your body will take it from your bones, which is one of the reasons why the combination of vitamin D and calcium is so important for strong, healthy bones as you age.

Studies also show that sufficient vitamin D supplementation in older adults can lower the risk of osteoporosis and bone fractures, especially fractures of the hip. One study in Minnesota found that elderly patients with fragility fractures-- not those caused by a fall-- were all vitamin D deficient.

Muscle Health

There are dozens of studies which show vitamin D can improve muscle mass, strength and endurance. Researchers have linked vitamin D levels with muscle function. People with higher vitamin D levels had better muscle function and vice versa. And when it comes to elderly people, researchers found that vitamin D supplementation improves muscle strength, muscle function, balance, and physical reaction time.

How does vitamin D work? Laboratory and clinical science shows that vitamin D increases oxygen content in the blood, which in turn increases blood supply to muscles. Studies also show that vitamin D can bind to specific cell receptors in muscle tissue and trigger protein synthesis which promotes the growth of muscle cells.

In Ancient Greece athletes believed that sunlight "feeds the muscles" and they would exercise naked on the beaches in an activity called arenation. In the early part of this century, doctors using sunlight to treat children with tuberculosis reported that their young patients had excellent lean, toned muscle mass. And modern day science has shown sunlight combined with physical exercise produces two to three times more stamina and muscular development than exercise alone.

Vitamin D has been clinically shown to be especially helpful in fighting age-related loss of muscle mass and strength, a condition called sarcopenia.

Heart Health

The heart health benefits of vitamin D are rarely discussed, but one study showed that UV exposure increases cardiac output by as much as 39 percent in over two-thirds of patients. UV exposure can also help protect arteries against clogs and improve circulation in patients with already clogged arteries.

Numerous studies have shown that sunlight and vitamin D can reduce inflammation and even help lower cholesterol.

On the flip side, a deficiency of vitamin D can weaken heart function and is linked to heart failure. Doctors have long pointed out that there are more heart attacks during the winter months, when sun exposure is often diminished.

Metabolic Health

Vitamin D plays a role in the secretion of insulin by the pancreas, thus helping to regulate blood sugar levels and potentially reducing the risk of Type-2 diabetes. What's more, studies show that vitamin D affects weight gain and weight loss. For example, when researchers looked at vitamin D intake and weight they found an inverse correlation. Those with greater vitamin D levels weighed less and those with lower vitamin D levels weighed more. In fact, obesity is associated with vitamin D deficiency.

Immune Function

If you've ever asked why more people get sick in the winter, you might be met with the fact that there are more germs and viruses floating around then. But some researchers say it's also caused by lowerred immunity from lack of vitamin D and sunlight.

In the book Sunlight, Dr. Zane Kime, MD examines the relationship between sunlight and your immune system. He writes: “Studies have shown that exposure to ultraviolet light or natural sunlight (but not enough to redden the skin) increases the number of white blood cells in the human blood. Amazingly the white blood cells that increase the most is the lymphocytes that play a leading role in defending the body against an invasion of germs. Because the lymphocytes increase… their products of defense, antibodies, also increase in the blood. In laboratory animals this effect may last as long as three weeks.”

Sunlight also increases neutrophils. These are the white blood cells that neutralize foreign matter. Viruses for example, or bacteria that enter into your bloodstream through a cut in your arm. Some studies have shown the effectiveness of neutrophils doubling when exposed to UV light

Other Health Benefits

Vitamin D also:

While both vitamin D and D3 offer these benefits, research indicates vitamin D3 is the more effective and preferred form. Vitamin D3 is more easily absorbed and utilized by the body, leading to higher and more sustained blood levels of vitamin D.

Food Sources of Vitamin D

To ensure adequate vitamin D intake, it's recommended to get regular safe sun exposure so that vitamin D can be naturally produced in the body. In addition, consume vitamin D-rich foods like fatty fish, fortified orange juice and fortified dairy, and consider a vitamin D3 supplement if needed. Consulting with a healthcare provider can help determine the appropriate dosage based on individual needs.

Vitamin D2 is primarily derived from plant sources, such as wild mushrooms and fortified foods like milk and breakfast cereals. Meanwhile, vitamin D3 is the form of vitamin D that the human body naturally produces when the skin is exposed to sunlight. It's also found in animal-sourced foods like oily fish, fish oil, liver, and egg yolks.

Symptoms of Vitamin D Deficiency

While many people with vitamin D deficiency don't notice any symptoms of a vitamin D deficiency, some potential signs include these common health complaints:

  • Muscle pain

  • Bone pain

  • Increased sensitivity to pain

  • Tingling or "pins-and-needles" sensation in the hands or feet

  • Muscle weakness, especially in the upper arms or thighs

  • Waddling gait due to muscle weakness in the hips or legs

  • History of broken bones

  • Muscle twitches or tremors

  • Muscle spasms

  • Bowed legs (in severe cases of deficiency

  • Fatigue and frequent illness

  • Anxiety

  • Slower wound healing

How To Supplement With Vitamin D

Absorption and Effectiveness

Research shows that vitamin D3 is more easily absorbed and utilized by the body when compared to vitamin D2. Vitamin D3 is more effective at raising and maintaining healthy blood levels of vitamin D, so dietary supplements containing D3 are preferred.

The body can convert vitamin D3 into the active form of vitamin D (calcitriol) more efficiently than vitamin D2.

Dosage and Availability

Vitamin D2 is available in both prescription (up to 50,000 IU) and over-the-counter formulations, while vitamin D3 is usually only available over-the-counter. The recommended daily allowance (RDA) of vitamin D varies by age and health status. The RDA for adults up to age 70 is 600 international units (IU) per day. Above age 70 it's 800. Most experts however recommend 2000 to 3000 IU per day for adults as being an appropriate dose, but many people need more. The only way to know for sure how much vitamin D you need is to take a test.

Testing Your Vitamin D Levels

The Endocrine Society recommends maintaining blood levels between 40 and 60 ng/mL for both adults and children. The Grassroots Health Nutrient Research Institute, a non-profit public health research organization with a panel of 48 senior vitamin D researchers, also recommends keeping levels between 40 and 60.

However, any number of doctors and studies we’ve consulted suggest the ideal blood level should be above 60 ng/ml. According to one doctor we interviewed, who has tested the D levels of hundreds of patients, she virtually NEVER sees anyone with a level above 60. But at the same time, the levels she does see vary all over the place, from patient to patient.

The only way to know for sure how much vitamin D you need is to have a blood test. Then, if you’re deficient, you can start with very high doses of D – say, 20,000 units a day – testing regularly until you get your blood level at least into the 50s. Once you’ve achieved that, ratchet down to a lower dose, testing frequently until you figure out what your long-term, maintenance amount should be to make sure you're getting enough vitamin D.

Fortunately, there are also at-home vitamin D finger stick tests available. We recommend having a lab test done first, to get a more reliable number, then maybe follow up with the home test, if you decide to go that route.


Vitamin D is essential for healthy aging and impacts nearly every part of your body from your heart to your bones. Vitamin D takes several different forms including vitamin D2 and D3.Vitamin D3 appears to be the more effective and preferred form due to its superior absorption and utilization by the body. Consulting with a healthcare provider can help determine the appropriate vitamin D supplement and dosage based on individual needs.

Frequently Asked Questions

Is it better to take vitamin D or D3?

Vitamin D supplements are best taken in the form of vitamin D3 to optimize absorption and health benefits.

Is vitamin D3 the same as just vitamin D?

Both vitamin D and vitamin D3 can maintain blood levels of circulating vitamin D known as 25-hydroxyvitamin D, but D3 is more efficient at achieving this. In addition, vitamin D3 has a different molecular structure and works in different ways in the body.

Why do doctors prescribe vitamin D instead of D3?

Medical authorities and most doctors regard D2 and D3 as equivalent, so a prescription is normally always in the form of vitamin D as D2 although D3 can also be prescribed in certain circumstance such as for people with celiac disease who would have absorption problems with D2.

Is it OK to take vitamin D3 everyday?

Yes. Dr. Michael Holick, a world leading authority on vitamin D recommends 2000-3000 IU daily for adults. He personally takes 3000 IU a day and this maintains his blood levels at around 55 ng/mL. Some natural health doctors still consider this blood level of vitamin D on the low side.

Alayed Albarri EM, et al. Qatar Med J. 2022 Aug 4;2022(3):29. Effectiveness of vitamin D2 compared with vitamin D3 replacement therapy in a primary healthcare setting: a retrospective cohort study.

Durrant LR, et al. Front Immunol. 2022 Feb 24;13:790444. Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System Revealed Through Analysis of the Blood Transcriptome.

Holick MF. Rev Endocr Metab Disord. 2017 Jun;18(2):153-165. The vitamin D deficiency pandemic: Approaches for diagnosis, treatment and prevention.

Logan VF, et al. Br J Nutr. 2013 Mar 28;109(6):1082-8. Long-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over the winter months.

Shieh A, et al. J Clin Endocrinol Metab. 2016 Aug;101(8):3070-8. Effects of High-Dose Vitamin D2 Versus D3 on Total and Free 25-Hydroxyvitamin D and Markers of Calcium Balance. .

Tripkovic L, et al. Am J Clin Nutr. 2012 Jun;95(6):1357-64. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis.

Tripkovic L, et al. Am J Clin Nutr. 2017 Aug;106(2):481-490. Daily supplementation with 15 μg vitamin D2 compared with vitamin D3 to in rease wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial.

van den Heuvel EG Adv Nutr. 2024 Jan;15(1):100133. Comparison of the Effect of Daily Vitamin D2 and Vitamin D3 Supplementation on Serum 25-Hydroxyvitamin D Concentration (Total 25(OH)D, 25(OH)D2, and 25(OH)D3) and Importance of Body Mass Index: A Systematic Review and Meta-Analysis

Zhang Y et al. BMJ. 2019 Aug 12;366:l4673. Association between vitamin D supplementation and mortality: systematic review and meta-analysis.

Bone & Muscle Defense

Bone & Muscle Defense

Derived from the amino acid leucine, myHMB®️ is a highly concentrated, proprietary breakthrough in muscle support and protection. Along with myHMB®️, Bone and Muscle Defense also contains the patented nutrient OsteoSine®, to support healthy bones, and is rounded out with clinical dosages of Vitamin D3, a potent and patented form of K2 called K2Vital®, Magnesium, and L-Carnitine, for the most complete bone and muscle support formulation available today.


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